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A 40-year-old man presented to the emergency department with two hours of rapid regular palpitations and dizziness. He denied vertigo, chest pain, shortness of breath, and syncope, and he said he had never had palpitations like this. His symptoms started suddenly and are continuous. He denied any significant prior medical history and tobacco, alcohol, and drug use, and he takes no prescription medications.

Exam

His vital signs were normal except for a softish blood pressure of 101/84 mm Hg and a pulse rate of 196 bpm. His head and neck exam was normal with no thyromegaly or jugular vein distention. His lungs were clear, and his heart was regular but tachycardic. The abdomen was benign, and the legs had no chords, tenderness, or edema.

Testing

The precordial leads of an ECG:

​Questions

What is the rhythm?

What is initial treatment of choice?

What is the second-line treatment?

What medication is overused for this condition?

Answers

The patient's rhythm is supraventricular tachycardia (SVT), and the initial treatment should be a modified Valsalva maneuver. The second-line treatment is diltiazem. Adenosine is overused for this condition.

SVT: Rate 125-250 and regular. If the rate is under 200, consider Wolff-Parkinson-White syndrome.

SVT is a regular tachycardia that usually has a paroxysmal onset and a regular rate between 125 and 250 with no P waves and a narrow QRS. Symptoms are primarily palpitations and lightheadedness. Chest pain, dyspnea on exertion, and syncope or near-syncope may also occur. Most cases are idiopathic, but SVT can be triggered by a variety of cardiac conditions as well as certain antidepressants. Low potassium and magnesium may also contribute.

Treatment of SVT has been primarily with adenosine in the recent past. A Valsalva maneuver may be tried first, but success rates are only about 15 percent. Recent studies have shown there is a better medication and a better Valsalva maneuver. The modified Valsalva, which consists of a Valsalva for at least 15 seconds followed by a passive leg raise, has been shown to terminate SVT in about 40 percent of patients. Diltiazem, with an initial dose of 15 mg, has been shown to be about 10 percent more effective than adenosine, with the additional benefits of a better safety profile, decreased cost, and patient preference.

Patients diagnosed with SVT can usually be discharged home with cardiology follow-up. Prevention for frequent or severe episodes may include beta or calcium channel blockers and ablation by an electrophysiologist.

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Posted by Brady Pregerson, MD at 1:27 AM

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About the Author

Brady Pregerson, MD

Dr. Pregerson is an emergency physician at Cedars-Sinai Medical Center in Los Angeles and Tri-City Medical Center in Oceanside. He is the author of Emergency Medicine 1-Minute Consult, Tarascon Emergency Department Quick Reference Guide, A to Z Emergency Pharmacopoeia & Antibiotic Guide, Don't Try This at Home, and Think Twice: More Lessons from the ER. He is a former Peace Corps volunteer and the winner of the 1995 Wise Preventive Medicine Scholarship at UC San Diego School of Medicine. Follow him on Twitter @QuickEssentials, and visit his website at EMresource.org, which has an emergency medicine ultrasound library, emergency medicine challenge cases, an essential ECG web page, and other resources and products for emergency medicine providers.